How can I repair a door closer that doesn't damp any more?

Hi Guido,

There are multiple ways that your issue arises,

And thus there are multiple steps to fix this issue.

My first suggestion would be to see if the system can be tightened through conventional means. this can usually be done by tightening the screw on the side of the main enclosure (Usually on the right). It may be that you only have a disc with two holes for a tool, but turning that clockwise should tighten the spring. Another option is to see if the top bar can be adjusted, but I personally recommend against this action.

Please let me know if I can assist you further.